I don't think merely writing characters will make you memorise them.
Nor is it the sole part of how kanji are traditionally learnt. However it is an adjunct to memorising them and for Japanese schoolchildren at least, the ability to write them and good penmanship are useful skills.
Rote-memorisation is used in a lot of subject areas, or not-so-rote by using Flashcards.
Personally I like writing kanji. For it's own sake. I like Shodo. I like the shapes, I like the potential beauty in kanji. I like understanding the actual etymology of characters. I like finding out the actual names of the radicals. I like finding out the logic underlying them. I find it useful to learn their readings and learn the kanji I use day to day. Heisig I find didn't
do this for me.
But I agree Heisig's worth a go. It might work for you.
It might help you "not forget" individual kanji.
I do think there is a natural progression in the, shall we call them, non-Heisig methods.
You start with simple characters describing natural phenomena such as 山、水、犬、人、母 and everyday activities 見る、読む、食べる where meanings are relatively easily ascribed to the shapes (象形), and work up to abstract or complex ideas and rarer characters 憲.
Generally you tend learn an English meaning first, then kun-yomi then on-yomi. Most likely using words that are in your own vocabulary. You can recognise, then read, then write. With the use of computers reading can be a productive skill in ensuring the IME's choice of kanji is correct.
I would say it's rare for someone to be able to recall amount of strokes or radical for a given character from memory. You are more likely to be able to stroke count and pick out a particular characters radical when you see it written. You are more likely to use general rules than to learn every individual kanji's stroke order.
Nor would it happen all at once. It's probably best to chunk the task. Working with groups of kanji you learn one thing at a time. Rather than everything about a character at once.
Groupings of kanji could be by shape or topic. or function.
With more complex kanji it might be worth chunking them as well. To see the components they are made of (hopefully from previous learnt characters) rather than the character as a whole. so you might see 懇 as comprising 豸（豕）、 艮（良） and 心、
you might remember it's reading コン as part of a word 懇話 [こんわ]friendly chat
and remember its general headword of sociable from this. or from the components 艮 (良) and 心、
If it's a kanji you use often or see often because perhaps your friends use it or it comes up in the subject matter of articles you are interested in you are more likely to remember it. (or if it's the name of your train station) I think you have stronger motivation and more hooks in your memory to learn and remember kanji you see and would make use of on a regular basis.
